Dissection of a novel molecular determinant mediating Golgi to trans-Golgi network transition.
Two major functions of the Golgi apparatus (GA) are formation of complex glycans and sorting of proteins destined for various subcellular compartments or secretion. To fulfill these tasks proper localization of the accessory proteins within the different sub-compartments of the GA is crucial. Here we investigate structural determinants mediating transition of the two glycosyltransferases beta-1,4- galactosyltransferase 1 (gal-T1) and the alpha-1,3-fucosyltransferase 6 (fuc-T6) from the trans-Golgi cisterna to the trans-Golgi network (TGN). Upon treatment with the ionophore monensin both glycosyltransferases are found in TGN-derived swollen vesicles, as determined by confocal fluorescence microscopy and density gradient fractionation. Both enzymes carry a signal consisting of the amino acids E(5)P(6) in gal-T1 and D(2)P(3) in fuc-T6 necessary for the transition of these glycosyltransferases from the trans-Golgi cisterna to the TGN, but not for their steady state localization in the trans-Golgi cisterna.
Schaub
B E
BE
Institute of Physiology, University of Zurich, Zurich, Switzerland.
Berger
E G
EG
Rohrer
J
J
D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D005647:Fucosyltransferases / Q000235:genetics / Q000378:metabolism*; D005700:Galactosyltransferases / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D008985:Monensin; D021381:Protein Transport / Q000502:physiology
D008985:Monensin; D005647:Fucosyltransferases; D005700:Galactosyltransferases; C119701:beta-1,4-galactosyltransferase I; C031692:galactoside 3-fucosyltransferase